Linaro-mm-sig December 2025

linaro-mm-sig@lists.linaro.org

56 participants
44 discussions

[PATCH RFC] mm/vmap: map contiguous pages in batches whenever possible

by Barry Song

From: Barry Song <v-songbaohua(a)oppo.com> In many cases, the pages passed to vmap() may include high-order pages—for example, the systemheap often allocates pages in descending order: order 8, then 4, then 0. Currently, vmap() iterates over every page individually—even the pages inside a high-order block are handled one by one. This patch detects high-order pages and maps them as a single contiguous block whenever possible. Another possibility is to implement a new API, vmap_sg(). However, that change seems to be quite large in scope. When vmapping a 128MB dma-buf using the systemheap, this RFC appears to make system_heap_do_vmap() 16× faster: W/ patch: [ 51.363682] system_heap_do_vmap took 2474000 ns [ 53.307044] system_heap_do_vmap took 2469008 ns [ 55.061985] system_heap_do_vmap took 2519008 ns [ 56.653810] system_heap_do_vmap took 2674000 ns W/o patch: [ 8.260880] system_heap_do_vmap took 39490000 ns [ 32.513292] system_heap_do_vmap took 38784000 ns [ 82.673374] system_heap_do_vmap took 40711008 ns [ 84.579062] system_heap_do_vmap took 40236000 ns Cc: Uladzislau Rezki <urezki(a)gmail.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: John Stultz <jstultz(a)google.com> Cc: Maxime Ripard <mripard(a)kernel.org> Signed-off-by: Barry Song <v-songbaohua(a)oppo.com> --- mm/vmalloc.c | 49 +++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 43 insertions(+), 6 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 0832f944544c..af2e3e8c052a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -642,6 +642,34 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, return err; } +static inline int get_vmap_batch_order(struct page **pages, + unsigned int stride, + int max_steps, + unsigned int idx) +{ + /* + * Currently, batching is only supported in vmap_pages_range + * when page_shift == PAGE_SHIFT. + */ + if (stride != 1) + return 0; + + struct page *base = pages[idx]; + if (!PageHead(base)) + return 0; + + int order = compound_order(base); + int nr_pages = 1 << order; + + if (max_steps < nr_pages) + return 0; + + for (int i = 0; i < nr_pages; i++) + if (pages[idx + i] != base + i) + return 0; + return order; +} + /* * vmap_pages_range_noflush is similar to vmap_pages_range, but does not * flush caches. @@ -655,23 +683,32 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift) { unsigned int i, nr = (end - addr) >> PAGE_SHIFT; + unsigned int stride; WARN_ON(page_shift < PAGE_SHIFT); + /* + * Some users may allocate pages from high-order down to order 0. + * We roughly check if the first page is a compound page. If so, + * there is a chance to batch multiple pages together. + */ if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || - page_shift == PAGE_SHIFT) + (page_shift == PAGE_SHIFT && !PageCompound(pages[0]))) return vmap_small_pages_range_noflush(addr, end, prot, pages); - for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { - int err; + stride = 1U << (page_shift - PAGE_SHIFT); + for (i = 0; i < nr; ) { + int err, order; - err = vmap_range_noflush(addr, addr + (1UL << page_shift), + order = get_vmap_batch_order(pages, stride, nr - i, i); + err = vmap_range_noflush(addr, addr + (1UL << (page_shift + order)), page_to_phys(pages[i]), prot, - page_shift); + page_shift + order); if (err) return err; - addr += 1UL << page_shift; + addr += 1UL << (page_shift + order); + i += 1U << (order + page_shift - PAGE_SHIFT); } return 0; -- 2.39.3 (Apple Git-146)

8 months

[PATCH v4 00/13] drm/amdgpu: preparation patchs for the use all SDMA instances series

by Pierre-Eric Pelloux-Prayer

This series is a subset of the "use all SDMA instances" series. It starts at the first modified patch and ends at the last patch before the drm/ttm patch that got merged through drm-misc-next. v3 of the full series: https://lists.freedesktop.org/archives/dri-devel/2025-November/537830.html Pierre-Eric Pelloux-Prayer (13): drm/amdgpu: introduce amdgpu_ttm_buffer_entity drm/amdgpu: add amdgpu_ttm_job_submit helper drm/amdgpu: fix error handling in amdgpu_copy_buffer drm/amdgpu: pass the entity to use to amdgpu_ttm_map_buffer drm/amdgpu: pass the entity to use to ttm public functions drm/amdgpu: statically assign gart windows to ttm entities drm/amdgpu: remove AMDGPU_GTT_NUM_TRANSFER_WINDOWS drm/amdgpu: add missing lock in amdgpu_benchmark_do_move drm/amdgpu: check entity lock is held in amdgpu_ttm_job_submit drm/amdgpu: double AMDGPU_GTT_MAX_TRANSFER_SIZE drm/amdgpu: use larger gart window when possible drm/amdgpu: introduce amdgpu_sdma_set_vm_pte_scheds drm/amdgpu: move sched status check inside amdgpu_ttm_set_buffer_funcs_status drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 + drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c | 5 +- drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 13 +- drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 8 +- drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 8 +- drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 4 +- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 295 ++++++++++++------ drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 54 +++- drivers/gpu/drm/amd/amdgpu/amdgpu_vce.c | 6 +- drivers/gpu/drm/amd/amdgpu/amdgpu_vce.h | 3 +- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 17 + drivers/gpu/drm/amd/amdgpu/cik_sdma.c | 31 +- drivers/gpu/drm/amd/amdgpu/sdma_v2_4.c | 31 +- drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c | 31 +- drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c | 35 +-- drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c | 35 +-- drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c | 31 +- drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c | 31 +- drivers/gpu/drm/amd/amdgpu/sdma_v6_0.c | 29 +- drivers/gpu/drm/amd/amdgpu/sdma_v7_0.c | 29 +- drivers/gpu/drm/amd/amdgpu/si_dma.c | 31 +- drivers/gpu/drm/amd/amdgpu/vce_v1_0.c | 12 +- drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 25 +- 23 files changed, 381 insertions(+), 385 deletions(-) -- 2.43.0

8 months

[PATCH] dma-buf: heaps: Clear CMA pages with clear_page()

by Linus Walleij

clear_page() translates into memset(*p, 0, PAGE_SIZE) on some architectures, but on the major architectures it will call an optimized assembly snippet so use this instead of open coding a memset(). Signed-off-by: Linus Walleij <linus.walleij(a)linaro.org> --- drivers/dma-buf/heaps/cma_heap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index 0df007111975..9eaff80050f2 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -315,7 +315,7 @@ static struct dma_buf *cma_heap_allocate(struct dma_heap *heap, while (nr_clear_pages > 0) { void *vaddr = kmap_local_page(page); - memset(vaddr, 0, PAGE_SIZE); + clear_page(vaddr); kunmap_local(vaddr); /* * Avoid wasting time zeroing memory if the process --- base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787 change-id: 20251129-dma-buf-heap-clear-page-248bb236e4c4 Best regards, -- Linus Walleij <linus.walleij(a)linaro.org>

8 months

Re: [PATCH v17 44/47] dept: introduce APIs to set page usage and use subclasses_evt for the usage

by Byungchul Park

On Thu, Oct 02, 2025 at 05:12:44PM +0900, Byungchul Park wrote: > False positive reports have been observed since dept works with the > assumption that all the pages have the same dept class, but the class > should be split since the problematic call paths are different depending > on what the page is used for. > > At least, ones in block device's address_space and ones in regular > file's address_space have exclusively different usages. > > Thus, define usage candidates like: > > DEPT_PAGE_REGFILE_CACHE /* page in regular file's address_space */ > DEPT_PAGE_BDEV_CACHE /* page in block device's address_space */ > DEPT_PAGE_DEFAULT /* the others */ 1. I'd like to annotate a page to DEPT_PAGE_REGFILE_CACHE when the page starts to be associated with a page cache for fs data. 2. And I'd like to annotate a page to DEPT_PAGE_BDEV_CACHE when the page starts to be associated with meta data of fs e.g. super block. 3. Lastly, I'd like to reset the annotated value if any, that has been set in the page, when the page ends the assoication with either page cache or meta block of fs e.g. freeing the page. Can anyone suggest good places in code for the annotation 1, 2, 3? It'd be totally appreciated. :-) Byungchul > Introduce APIs to set each page's usage properly and make sure not to > interact between at least between DEPT_PAGE_REGFILE_CACHE and > DEPT_PAGE_BDEV_CACHE. However, besides the exclusive usages, allow any > other combinations to interact to the other for example: > > PG_locked for DEPT_PAGE_DEFAULT page can wait for PG_locked for > DEPT_PAGE_REGFILE_CACHE page and vice versa. > > PG_locked for DEPT_PAGE_DEFAULT page can wait for PG_locked for > DEPT_PAGE_BDEV_CACHE page and vice versa. > > PG_locked for DEPT_PAGE_DEFAULT page can wait for PG_locked for > DEPT_PAGE_DEFAULT page. > > Signed-off-by: Byungchul Park <byungchul(a)sk.com> > --- > include/linux/dept.h | 31 +++++++++++++++- > include/linux/mm_types.h | 1 + > include/linux/page-flags.h | 76 +++++++++++++++++++++++++++++++++++++- > 3 files changed, 104 insertions(+), 4 deletions(-) > > diff --git a/include/linux/dept.h b/include/linux/dept.h > index 0ac13129f308..fbbc41048fac 100644 > --- a/include/linux/dept.h > +++ b/include/linux/dept.h > @@ -21,8 +21,8 @@ struct task_struct; > #define DEPT_MAX_WAIT_HIST 64 > #define DEPT_MAX_ECXT_HELD 48 > > -#define DEPT_MAX_SUBCLASSES 16 > -#define DEPT_MAX_SUBCLASSES_EVT 2 > +#define DEPT_MAX_SUBCLASSES 24 > +#define DEPT_MAX_SUBCLASSES_EVT 3 > #define DEPT_MAX_SUBCLASSES_USR (DEPT_MAX_SUBCLASSES / DEPT_MAX_SUBCLASSES_EVT) > #define DEPT_MAX_SUBCLASSES_CACHE 2 > > @@ -390,6 +390,32 @@ struct dept_ext_wgen { > unsigned int wgen; > }; > > +enum { > + DEPT_PAGE_DEFAULT = 0, > + DEPT_PAGE_REGFILE_CACHE, /* regular file page cache */ > + DEPT_PAGE_BDEV_CACHE, /* block device cache */ > + DEPT_PAGE_USAGE_NR, /* nr of usages options */ > +}; > + > +#define DEPT_PAGE_USAGE_SHIFT 16 > +#define DEPT_PAGE_USAGE_MASK ((1U << DEPT_PAGE_USAGE_SHIFT) - 1) > +#define DEPT_PAGE_USAGE_PENDING_MASK (DEPT_PAGE_USAGE_MASK << DEPT_PAGE_USAGE_SHIFT) > + > +/* > + * Identify each page's usage type > + */ > +struct dept_page_usage { > + /* > + * low 16 bits : the current usage type > + * high 16 bits : usage type requested to be set > + * > + * Do not apply the type requested immediately but defer until > + * after clearing PG_locked bit of the folio or page e.g. by > + * folio_unlock(). > + */ > + atomic_t type; /* Update and read atomically */ > +}; > + > struct dept_event_site { > /* > * event site name > @@ -562,6 +588,7 @@ extern void dept_hardirqs_off(void); > struct dept_key { }; > struct dept_map { }; > struct dept_ext_wgen { }; > +struct dept_page_usage { }; > struct dept_event_site { }; > > #define DEPT_MAP_INITIALIZER(n, k) { } > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 5ebc565309af..8ccbb030500c 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -224,6 +224,7 @@ struct page { > struct page *kmsan_shadow; > struct page *kmsan_origin; > #endif > + struct dept_page_usage usage; > struct dept_ext_wgen pg_locked_wgen; > } _struct_page_alignment; > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index d3c4954c4218..3fd3660ddc6f 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -204,6 +204,68 @@ enum pageflags { > > extern struct dept_map pg_locked_map; > > +static inline int dept_set_page_usage(struct page *p, > + unsigned int new_type) > +{ > + unsigned int type = atomic_read(&p->usage.type); > + > + if (WARN_ON_ONCE(new_type >= DEPT_PAGE_USAGE_NR)) > + return -1; > + > + new_type <<= DEPT_PAGE_USAGE_SHIFT; > +retry: > + new_type &= ~DEPT_PAGE_USAGE_MASK; > + new_type |= type & DEPT_PAGE_USAGE_MASK; > + > + if (!atomic_try_cmpxchg(&p->usage.type, &type, new_type)) > + goto retry; > + > + return 0; > +} > + > +static inline int dept_reset_page_usage(struct page *p) > +{ > + return dept_set_page_usage(p, DEPT_PAGE_DEFAULT); > +} > + > +static inline void dept_update_page_usage(struct page *p) > +{ > + unsigned int type = atomic_read(&p->usage.type); > + unsigned int new_type; > + > +retry: > + new_type = type & DEPT_PAGE_USAGE_PENDING_MASK; > + new_type >>= DEPT_PAGE_USAGE_SHIFT; > + new_type |= type & DEPT_PAGE_USAGE_PENDING_MASK; > + > + /* > + * Already updated by others. > + */ > + if (type == new_type) > + return; > + > + if (!atomic_try_cmpxchg(&p->usage.type, &type, new_type)) > + goto retry; > +} > + > +static inline unsigned long dept_event_flags(struct page *p, bool wait) > +{ > + unsigned int type; > + > + type = atomic_read(&p->usage.type) & DEPT_PAGE_USAGE_MASK; > + > + if (WARN_ON_ONCE(type >= DEPT_PAGE_USAGE_NR)) > + return 0; > + > + /* > + * event > + */ > + if (!wait) > + return 1UL << type; > + > + return (1UL << DEPT_PAGE_DEFAULT) | (1UL << type); > +} > + > /* > * Place the following annotations in its suitable point in code: > * > @@ -214,20 +276,28 @@ extern struct dept_map pg_locked_map; > > static inline void dept_page_set_bit(struct page *p, int bit_nr) > { > + dept_update_page_usage(p); > if (bit_nr == PG_locked) > dept_request_event(&pg_locked_map, &p->pg_locked_wgen); > } > > static inline void dept_page_clear_bit(struct page *p, int bit_nr) > { > + unsigned long evt_f; > + > + evt_f = dept_event_flags(p, false); > if (bit_nr == PG_locked) > - dept_event(&pg_locked_map, 1UL, _RET_IP_, __func__, &p->pg_locked_wgen); > + dept_event(&pg_locked_map, evt_f, _RET_IP_, __func__, &p->pg_locked_wgen); > } > > static inline void dept_page_wait_on_bit(struct page *p, int bit_nr) > { > + unsigned long evt_f; > + > + dept_update_page_usage(p); > + evt_f = dept_event_flags(p, true); > if (bit_nr == PG_locked) > - dept_wait(&pg_locked_map, 1UL, _RET_IP_, __func__, 0, -1L); > + dept_wait(&pg_locked_map, evt_f, _RET_IP_, __func__, 0, -1L); > } > > static inline void dept_folio_set_bit(struct folio *f, int bit_nr) > @@ -245,6 +315,8 @@ static inline void dept_folio_wait_on_bit(struct folio *f, int bit_nr) > dept_page_wait_on_bit(&f->page, bit_nr); > } > #else > +#define dept_set_page_usage(p, t) do { } while (0) > +#define dept_reset_page_usage(p) do { } while (0) > #define dept_page_set_bit(p, bit_nr) do { } while (0) > #define dept_page_clear_bit(p, bit_nr) do { } while (0) > #define dept_page_wait_on_bit(p, bit_nr) do { } while (0) > -- > 2.17.1

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